The present technology relates to a signal processing device, to a method of processing a signal, and to a recording medium. Specifically, the present technology relates to a signal processing device, a method of processing a signal, and a recording medium that detect a predetermined signal and to allow the detected signal to be processed.
In recent years, an RFID (Radio Frequency Identification) system has been widely spread. The RFID system attaches information (identification information) for identifying an individual such as a device, a package, a human, and other living thing to the individual with the use of a device called “RF tag”. In the RFID system, a wireless transceiver called “reader-writer” and the tag perform wireless communication therebetween.
Typically, the RFID system stores data in a built-in semiconductor memory, reads the data in the semiconductor memory, and transmits the read data by short-distance communication through an induced electromagnetic field or a radio wave. Alternatively, the RFID system receives transmitted data, and writes the received data in the semiconductor memory. In particular, a device that reads the data from the RFID is called “reader”, and a device that writes the data in the RFID is called “writer”. In general, an information medium that is an RFID capable of at least reading stored data is called “RF tag”.
The RFID is configured of a semiconductor integrated circuit chip including an antenna and a semiconductor memory, and receives a radio wave with the use of the antenna. Some RFIDs generate electric power necessary for operation with the use of the received radio wave or electromagnetic coupling with the reader or the writer. The RFID that communicates with the reader generates a reflected wave that is varied depending on the stored data (by varying a load of the electromagnetic coupling), and allows the reader to read the data.
It is to be noted that the RF tag is also referred to as a data carrier, a transponder, a smart card, an intellitag, a wireless IC tag, a non-contact type IC tag, etc.
The reader in the RFID system may have, for example, a function to detect a signal pattern that represents a first data frame (SOF: Start Of Frame) included in the signal transmitted from the RF tag. In some RFID system standards, two different signal patterns are provided for SOF. For example, a signal pattern of an SOF in accordance with International Standard ISO15693 has two patterns, that are, a pattern of “One Subcarrier” and a pattern of “Two Subcarriers”.
Japanese Unexamined Patent Publication Application (Translation of PCT Application) No. 2009-508384 (JP2009-508384A) discloses a device that detects an SOF corresponding to “One Subcarrier”. JP2009-508384A proposes a method to determine a cross-correlation function between the received signal and the reference SOF pattern, and to detect a timing of the SOF based on the time when a value of the cross-correlation function reaches a peak.